Adjustable stop for spacing devices



l' fwd sept. 4, 1956 G. D. STOUGH ADJUSTABLE STOP FOR SPACING DEVICES Filed March 28, 1955 INVENTOR.

GERALD D. STOUGH MMM/31%@ ATTORNEYS United States Patent() ADJUSTABLE STOP FOR SPACING DEVICES Gerald D. Stough, Detroit, Mich., assignor to Whitehead & Kales Company, River Rouge, Mich., a corporation of Michigan Application March 28, 1955, Serial No. 497,126

Claims. (Cl. 164-117) The invention relates to adjustable stop blocks designed for being variably positioned in a track to control the successive positions of rest of an intermittently advanced carriage. Such constructions are used in connection with -the feeding of Work in punch presses and other machine tools.

Heretofore, constructions of such character have been in use in which the blocks are variably positioned between parallel rack bars, the teeth of which are offset so that each tooth of one bar is opposite a space between adjacent teeth of the other bar. Correspondingly offset teeth on opposite ends of the block are engageable with said racks and the position of the yblock longitudinally of the racks will be changed by reversing said blocks end to end and also by rotating the block through one-half revolution. Thus, the space between centers of adjacent rack teeth may be divided into four equal parts, each of which corresponds to a possible position of the block when engaged with the rack bars. To provide suiicient strength and rigidity to the apparatus, the rack teeth must ybe of a minimum size and, consequently, the increments between successive positions of adjustment of the blocks are thus determined.

Itis the object of the invention to obtain a construction of stop block which, without detrimental decrease in strength, is capable of adjustment with smaller increments between successive positions. To this end, the invention consists in ythe construction as hereinafter set forth.

In the drawings:

Fig. 1 is a plan view showing the spaced rack bars of the track and a stop block in engagement therewith.

Fig. 2 is a perspective view of the stop block.

Fig. 3 is an end elevation of a stop block slightly modied in construction.

Figs. 4 to 11 are diagrams showing the successive positions of adjustment of the stop block within a dimension equal to the spacing between successive rack teeth.

In common with constructions heretofore used, the spacing apparatus includes parallel rack bars A, A1 having substantially square teeth A2 which are offset so that each tooth of one bar is opposite an interdental space of the other bar. Also, there is a stop block B having correspondingly oset teeth C, C1 at its opposite ends which are engageable with said racks in different positions longitudinally thereof when reversed end for end or rotated through one-half revolutions. Thus, as above stated, the space between centers of adjacent rack teeth is divided into four equal parts and the block can -be advanced in its engagement with the rack bars by increments equal to this one-fourth dimension.

To adapt this structure to advancement by smaller increments, the teeth at the opposite ends of the stop block are channeled transversely to form teeth in this transverse plane and these teeth are correspondingly -otfset at the opposite ends of the block. This permits of `turning the block one-fourth revolution and then engaging it with the rack hars. Also, the block may be further turned onehalf revolution and may be reversed end lfor end being engageable with the racks in each of said positions. In other Words, the block instead of having only four distinct positions for engagement with the rack now has eight positions. Between the ends of the block is a portion thereof forming the stop for the carriage, said portion being rectangular in cross section and of equal diameters transversely in this section. These diameters may be an odd multiple of a unit which is one-eighth the dimension between centers of 1the rack teeth and by properly positioning Ithis cross -section in relation to the teeth at the opposite ends of the block, the latter may be advanced longitudinally of the rack by such one-eighth unit increment. It is to be understood that the carriage (not shown) is stopped by fingers thereon Which embrace the cross section above mentioned.

As illustrated diagrammatically in Fig. 4, D is the por- `tion of the block which forms the stop for the carriage. D', D2, and D3 show successive positions of the portion D after each quarter turn thereof. D4, D5, D6, and DI correspond to the positions D-D3 inclusive after the block has been reversed end for end. The unit of increment in the successive positions of advancement of the block is one-eighth of the dimension between centers of adjacent rack teeth and it will be noted that the diameter of the portion D is 4seven times this uni-t. This however is not essential.

The stop block has, as illustrated in Fig. 2, only four separate teeth at each end. As shown in Fig. 3, 'there are six teeth which is the preferable construction as it is symmetrical and increases the strength. However, the number of teeth is not essential and may be varied.

What I claim as my invention is:

1. A stop block for variable positioning between spaced, parallel rack members `the teeth of which are offset to place each tooth of one of said Imembers opposite an interden-ta'l space of the other, said block having correspondingly oitset teeth at its opposite ends for engagement with said racks when reversed end for end or rotated through degrees to provide four different positions of said block, the teeth of said block at opposite ends thereof 'being transversely channeled with the channels correspondingly oiset to form interrupted teeth for engagement with said rack teeth when said block is rotated to a fifth position less than 180 degrees from one of said four positions and when rotated 180 degrees from said fth position and when reversed end for end to provide eight different positions of said block, the portion of said block intermediate its ends being eccentric and shaped Vto present an abutment surface facing in the same direction at eight different locations in each length of said racks equal to the distance between tooth centers thereof.

2. Structure as defined in claim l in which said channels extend perpendicular to the rst mentioned teeth of said block.

3. Structure as defined in claim 2 in which the intermediate portion of said block is of rectangular crosssection having surfaces parallel to said teeth and to said interrupted teeth.

4. Structure as defined in claim 3 in which the crosssectional shape of the intermediate portion is a square the sides of which have a length equal to an odd multiple of a unit equal to one-eighth of the dimension between centers of said rack teeth.

5. Structure yas defined in claim 1 in which the intermediate portion has equal Itransverse dimensions measured parallel to the teeth and interrupted teeth of said block equal to an odd multiple of a unit equal to one-eighth of the dimension `between centers of said rack teeth.

(References on following page) 1,445,796 Paxton Feb. 20, 1923 

